Telephone-exchange system



C. L. GOODRUM.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED DEC. 3|, 1919.

1,387,255, Patented Mg. 9,1921.

Van for 6/2 air/es L Gaadrum UNITED STATE PATENT OFFICE.

CHARLES L. eoonmmr. OFNEW YORK, a. Y., Assicnon r WESTERN ,ntnc'rmccom:- rANy, mcoaroaunn, or ivnwvonx, N. Y.,-A CORPORATION or NEW'YORK.

TELErHoivE-EXcnANeE SYSTEM.

To all whom it may concern: 7

Be it known that I, CHARLES L. GooDRUM,

a citizen of the United States, residing at New York, in the county ofNew York and 'State of New York, have invented certain new and usefulImprovements in Telephone Exchange Systems, of which the following is afull, clear, concise, andexact descripflt1on.

This invention relates to telephone exchange systems, and moreparticularly to circuit arrangements for selector switches employed inautomatic and semi-automatic telephone exchanges.

In systesms employing automatic switching appa rtus for extendingconnections froma calling to a calledsubscriber, it is customary tocontrol such switches by means of impulse-sending devices at the callingstation. These impulse senders or calling devices are of variousformsand are capable of sending impulses varying in character.Forexample, someimpulse senders are de signed to send a series ofimpulses corre-. sponding to the digit of the number desired 'in whichall of the interruptions between said impulses are of equal length,while others are designed to send a series of im pulses in whichall oithe interruptions between impulses are of equal length except the lastwhich is relatively longer than the preceding ones. An impulse-sendingdevice of thelatter nature is disclosed in Patent No. 1,158,951 ofNovember 2,1915, to A. H. Adams ct al. In the. well-known type ofselector switch'a controlling relay for sending impulses to an operatingmagnetat each interruption'of the line circuitcoiiperates with aslow-to-release relay which is energizedat the first closure of the linecircuit and remains energized during the sending of a se-' riesoffiimpulses. In the common type of selector switch a second slow relaysimilar to the onementioned above isused to control aso-called sideswitch through the-me diuin of a "magnet, the sideswitch being advancedafter each series of impulses to cliange local circuits in preparationfor the hunting movements. .Difliculty has loeen experienced with theordinary. selector switch when different type senders have been' used,

due to the stepping magnet oftheswitch not operating to step the switchin accordance with the digits setup at the impulse sender since, wherethe lastinterruption was longer than the preceding onesthe side switchemploying the present invention.

7 Specification of Lettcrslatent, P t t d u 9, 92 Aplilication filedDecember 31, 1919. Serial No. 34 579. i ii WOIld operate'before thelast'impulsewas I V e l l It is, therefore, an object of this inventionto provide a new and improved'circuit arrangement for a selector switch,whereby the operation of the stepping magnet for setting the switch inrelationto a group of trunk terminals-1s independent of the currentimpulses sent out by the impulse sender atthe calling station In thepresent embodimentof the inven tion, the stepping magnets for operatingthe selector sw tch are controlled by a relayin a local impulse circuit,which relay is in turn controlled in the directive selective movementsof the switch by the line relay. The

- circuit arrangement is such that the impulse. relay is shunted duringthe closure of the line circuit, said shunt being broken a t eacliinterruption duringthe sending of impulses, thereby permitting. theenergizatlon of the impulse relay. Actuation of the impulse relay closesa circuitfor the stepping mag nets, which, in turn, at their contactsagain form a short circuit path for the winding'of the impulse relay; 1V

The drawings represent diagrammatically a portion of a telephoneexchange "system Only so much of the circuit arrangements anda'pparatusis shown as is necessary. fora clear understanding of this invention I wThe mechanical construction and the operation of the step-by-stepselector switches and other apparatus used in building up a connectionbetween a calling and called subscriber are well known to those skilledin the art, and therefore, in the present disclosure a detaileddescription will be given only of the operation of the selector switchutilized in the establishment of a connection.

; The subscriber at substation A, desiring tov establish a connectionwith substation B, removes hls receiver fromthe switchhook and causes atrunk. finder or line switch C, to

Relay at upon energiz'ation closes .a-circuit from ground through itsright armature and release relay 11 to grounded battery. Re-

lay 11 upon energization prepares a circuit for relay 14 as follows:grounded battery, resistance 12, front contact and left hand armature ofrelay 11 and winding of relay 14 to ground. Relay 14 does notoperate atthis moment due to its being shunted at its right armature and backcontact and left armature and front contact of relay 4 to ground.

The calling subscriber now operates his impulse sender S, which may beof the type disclosed in the patent heretofore mentioned, to send aseries of impulses over the line to cause the setting of the selectorswitch D. Upon the first interruption of the line. circuit, line relay 4releases its armatures, thereby removing the shunt at its left-handarmature for relay 14, causing energization of the latter over the pathheretofore traced. Energization of relay 14 establishes a circuit forprimary stepping magnet 21, over the following path: ground, armatureand front contact of relay 14, side switch wiper20 in its firstposition, winding of primary stepping magnet 21 to grounded battery.Upon energization of primary stepping .magnet 21, its armature isattracted and a'sliunt path is prepared for relay 14 as follows:grounded battery, resistance 12, front contact and left hand armature ofrelay 11, armature and-front contact of magnet 21, side switch wiper 50and its first contact, and front contact and left-hand armature of ielay 4 to ground; This shunt "path is complete'd at the endof theinterruption of the line circuit, due to the armature of relay4 beingattracted when the second impulse of current is sent over the line. Thisopera tion is repeated for all impulses of the series.

In accordance with the nature of the impulse sender herein referred to,thelast interru'ption in a series of impulses will be a comparativelylong one which results in a comparatively long deenergization of theline relay and the closure of the back contact and right armaturethereof to ground. This results in the energization of escape magnet 15over the following path grounded battery, winding of magnet 15, sideswitch wiper 16, in its first position, resistance 17, front contact andright-hand armature of relay 11, back contact and right-hand arm-- tureof relay 4 to ground. Magnet 15 is of the slow-to-energize type and doesnot receive suflicient current during the preceding interruptions to"energize. As soon as the sending out of impulses ceases and the rightarmature of relay 4 is maintained attracted for a relatively longinterval, magnet 15 is deenergized, thus moving the side switch brushesinto position 2. Relay 14 was "enere g'ized and consequently energized:the (step;

"ping magnet 21, at the beginning of the interruption in the linecircuit, so that the last directive movement ofthe switch was completedbefore the side switch was moved into position 2. In position 2 of theside switch wipers, primary magnet 211s d sconnec-tecland secondarymagnet isfconnected tofground over,;.tl1e,, front contact andlefthandarmature of relay 14, relay 14 having been energized over the followingpath: grounded battery, resistance .12, front con-- tact and left-handarmature of 'relay 11, winding'of relay 14 toground;

. Under the control of magnet 22, the wipersof the selector switch arestepped over the terminals thereof'until an idle trunk is reached.Assoon as testbrush 26 of the selector switch D reachesthe terminal ofan idle trunk 27, to=which ground will b'e'c'onnected,'a circuit isclosed from this ground through brush 26, side switch lwiper 16 in itssecond position, winding OfPmagnot 15 to grounded battery. The escapemagnet 15 will again be energized causing the wiping apparatus (selectoror connector) win be restored to normal, causing, ground to be placeduponrthe terminal 27, engaged by brush 26s This will close a circuitfrom ground through brush 26 side switch wiper 19 in itsthirdpositionyoff-normal i contact 40 and winding. of unease magnet 30 togrounded battery. Release'inagnet 30,11pon energization, closes. alocking circuit for itself from grounded {battery through itsw-indingandoff-normal contact 40 and armature and. front contact to' ground. Underthe control of release inagnet 30, theselector switclif-D and'theassociated side switch will be restored: to normal, the locking circuitof the release magnet being maintainedclosed at its off-normal contactuntil selector switch Dhasbeen restored to its normal position?v Afterthe receiver offl'tlle calling substation A has been replaced and theside isw'itch hasbeen restored tofnorinal, a groundzis I sent throughthe right-hand arinatures and back contacts of relays 4 and 11 throughside switch wiper 31 in its first position to the-line or trunk finder Cfor causing the release of this switch." I Y Y 1 Should i the subscriberat" substation A abandon the call before sending out. impulses, he wouldieplacehis receiver on the switch'hook, :and cause thereby the Tdeenergiz-ation-ofline relay 4 and slow release re- 7 tion.

after the first set of impulseshave been sent,

2'. 6., when the side switch wipers are in position 2, relays 4 and 11would be deenergized and a circuit would be closed for release magnet 80over the path previouslytraced which would cause the restoration of these lector and line switch or "trunk finder to normal as heretoforedescribed. What is claimed is:

1. In a telephone exchangesystem, incoIn-' ing and outgoing groups oflines, a selector switch for extendlng an incoming topan outgoing line,an impulse sender associated with said incoming line vfor sending aseries of impulses 'thereover, a directively controlled magnet forsetting said selector switch in operative relation to a group ofoutgoing lines, an automatically operatin magnet for moving saidselector over lines in the selected group, a line relay responsive toclosures in said incoming line circuit, a slow-acting relay energizedduring the sending of a series of impulses, an impulse relay forcontrolling the actuation of said dir'ectively controlled and saidautomatically operating magnets, a winding for said impulse relay,

means for shunting said impulse relay upon actuation of said line relay,means for energizing said impulse relay, and a shunt circuit for thewinding of said impulse relay including contactson said magnetseffective upon energization of said magnets for causing thedeenergization of said impulse relay.

2. In a telephone exchange system, a line terminating in an automaticswitch having primary and secondary operating magnets, an impulse senderforsending a series of impulses over said line, and three relays onlyfor controlling the actuation of said magnets, oneoi'f saidrelaysbeingenergized during the sending of each impulse of current,another of said relays being energized during the sending of a series ofimpulses,

and the third relaybeing energized. during the intervals betweenimpulses.

3. In a telephone exchange system, a line, an automatic switch, astepping magnet therefor, an impulse sender for. sending a series ofimpulses over said line, a line relay responsive to each of the currentimpulses of a series, a slow acting relay energized during the sendingof all the impulses of a series, an

impulse relay energized at each interval between impulses forcontrolling said stepping magnet, and means for, shunting the winding ofsaid impulse relay upon its-energizar 4. The combination with a steppingmagnet, of a stepping relay having an armature and contact for closing'acircuit energizing said stepping magnet, a winding for said steppingrelay, a line circuit, a line relay, an impulse sender for sending aseries of impulses over said line to said line relay, and a shunt forthe winding of said stepping relay effective when said line. circuit isclosed, said shunt being removed when said line circuit is interrupted.I

. 5; The combination with a stepping mag- .net, of a stepping relayhaving an armature and contact for closing acircuit for energizing saidstepping magnet, a winding for said stepping relay, a line circuit, aline relay, a slow-acting relay, an impulse sender for sending a seriesof impulses over said line to said line relay, a shunt for the windingof said stepping relay effective when said line circuit is closed, saidshunt being removed when said line circuit is interrupted, and asecondshunt for the winding of said stepping relay effective when saidline circuit is closed and said stepping magnet is energized. a v

6. In a telephone system, an automatic switch having a plurality ofoperating magnets, a relay common to said magnets, means for associatingthe relay successively with I said magnets, means for intermittentlyenergizing the relay to operate said magnets, and means operable by theV magnet associated with the relay to intermittently short-circuit thewinding of the relay.

i. In a telephone system, a calling station,

.an automatic switch for extending a call therefrom, a line relay forsaid switch, a sender for said station for transmitting impulses to saidline relay, a stepping relay, a circuit'controlled by contacts of saidline relay completed for said stepping relay at the beginning of eachimpulse for operating said switch controlled by said stepping-re lay,and means for short-circuiting said stepping relay when said magnetoperates.

8. In a telephone system, a calling station, an automatic switch forextending a call therefrom, a line relay for said switch, a sender atsaid calling station for intermittently interrupting a circuit includingsaid line relay, stepping relay, a circuit closed for saidstepping relayat each deenergization ofsaid line relay, a stepping magnetfor saidswitch controlled by said stepping relay, and means for deenergizingsaid steppingrelay atthe end of each interruption in the circuit of saidline relay.

In witness whereof, I hereunto subscribe my name this 30th day ofDecember A. 1)., 1919.

, cnannns "L. coonn'UM.

. said stepping relay, a magnet for operating

